Introduction: Why Java Is Needed for Automation Testing (3 Years Experience)
When you reach around 3 years of experience in software testing, interview expectations increase significantly. Companies no longer look for someone who only knows Selenium commands or basic Java syntax. Instead, they expect a tester who:
- Writes clean and efficient Core Java code
- Understands why a framework is designed in a certain way
- Can solve real-time automation problems
- Has experience with Selenium, TestNG/JUnit, API testing, and CI/CD
- Can explain design decisions and trade-offs
That’s why java interview questions for 3 years experience in testing focus on Core Java depth + practical automation usage, not just definitions.
Core Java Topics for Testing (What Interviewers Expect at 3 Years)
At this experience level, interviewers expect conceptual clarity and practical usage.
1. Object-Oriented Programming (OOP)
- Inheritance & method overriding
- Runtime vs compile-time polymorphism
- Abstraction vs encapsulation
- Basic understanding of SOLID principles
2. Java Collections
- Internal working of List, Set, Map
- Performance differences
- When to use which collection
3. Exception Handling
- Checked vs unchecked exceptions
- Custom exceptions
- Exception propagation
4. Multithreading (Practical Level)
- Thread safety
- Synchronization basics
- Parallel execution in TestNG
5. Java 8 Features
- Streams and filters
- Lambda expressions
- forEach vs traditional loops
Java Interview Questions for 3 Years Experience in Testing (Core Java)
Q1. Why is Core Java important for a tester with 3 years experience?
Core Java is required to design frameworks, write reusable automation code, handle test data, and debug failures efficiently.
Q2. Explain JVM, JRE, and JDK.
- JVM – Executes Java bytecode
- JRE – JVM + runtime libraries
- JDK – JRE + development tools
Q3. What is runtime polymorphism?
Runtime polymorphism happens when a method call is resolved at runtime using method overriding.
class Browser {
void open() {
System.out.println(“Opening browser”);
}
}
class Chrome extends Browser {
@Override
void open() {
System.out.println(“Opening Chrome browser”);
}
}
public class Test {
public static void main(String[] args) {
Browser b = new Chrome();
b.open();
}
}
Output
Opening Chrome browser
Q4. Difference between abstraction and encapsulation?
- Abstraction hides implementation details
- Encapsulation hides data using access modifiers
Q5. What are SOLID principles?
A set of object-oriented design principles to make code maintainable and scalable.
Q6. Difference between ArrayList and HashSet?
- ArrayList → Allows duplicates, maintains order
- HashSet → No duplicates, no order guarantee
Q7. HashMap vs LinkedHashMap?
- HashMap → Faster, unordered
- LinkedHashMap → Maintains insertion order
Q8. Iterate a HashMap.
HashMap<String,String> map = new HashMap<>();
map.put(“browser”,”chrome”);
for(Map.Entry<String,String> entry : map.entrySet()){
System.out.println(entry.getKey() + ” : ” + entry.getValue());
}
Output
browser : chrome
Q9. What is a custom exception?
A user-defined exception created to handle business-specific errors.
Q10. Exception propagation example.
void readFile() throws IOException {
throw new IOException(“File not found”);
}
Q11. What is multithreading?
Executing multiple threads simultaneously to improve performance.
Q12. Why is Runnable preferred over Thread?
Because Java supports only single inheritance.
Q13. Java 8 Stream real-time example.
List<Integer> marks = Arrays.asList(40,60,80);
marks.stream().filter(m -> m >= 60).forEach(System.out::println);
Output
60
80
Q14. What is immutability?
Immutable objects cannot be modified after creation (example: String).
Q15. String vs StringBuilder?
- String → Immutable
- StringBuilder → Mutable and faster
Selenium Interview Questions for 3 Years Experience Testers
Q16. What challenges have you faced in Selenium?
Dynamic elements, synchronization issues, flaky tests, browser compatibility.
Q17. What is Selenium WebDriver?
WebDriver is an automation tool that directly controls browsers.
Q18. Implicit vs Explicit wait – which is better?
Explicit wait is better because it waits for specific conditions.
WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
wait.until(ExpectedConditions.visibilityOf(element));
Q19. How do you handle dynamic XPath?
Using contains() or starts-with() functions.
Q20. How do you handle frames?
Using driver.switchTo().frame().
Q21. How do you handle file upload?
Using sendKeys() with file path.
Q22. How do you capture screenshots?
File src = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);
Q23. How do you handle stale element exception?
Re-locate the element or apply proper waits.
Q24. How do you execute JavaScript in Selenium?
JavascriptExecutor js = (JavascriptExecutor) driver;
js.executeScript(“window.scrollBy(0,500)”);
Java Selenium Coding Challenges (3 Years Experience Level)
Q25. Automate login using Page Object Model.
Expected approach
- Page class with locators
- Test class with assertions
Q26. Find broken links on a page.
- Capture all <a> tags
- Validate HTTP response codes
Q27. Scroll until element is visible.
Use JavaScriptExecutor.
Q28. Handle multiple windows.
Use getWindowHandles().
Real-Time Interview Scenarios (Must-Know)
Scenario 1: Page Object Model (POM)
Explain:
- Why POM improves maintainability
- How pages and tests interact
Scenario 2: API + UI Validation
Steps
- Call API using Rest Assured
- Capture response
- Validate UI values
Scenario 3: Database Validation
Validate UI data against database using JDBC.
Scenario 4: CI/CD Integration
Explain how Jenkins triggers automation jobs.
JUnit Interview Questions for 3 Years Experience
Q29. What is JUnit?
JUnit is a unit testing framework for Java.
Q30. Common JUnit annotations?
- @Test
- @Before
- @After
TestNG Interview Questions for 3 Years Experience
Q31. Why TestNG is preferred over JUnit?
Supports parallel execution, grouping, reporting.
Q32. Important TestNG annotations?
- @BeforeSuite
- @BeforeMethod
- @AfterMethod
Q33. DataProvider example.
@DataProvider
public Object[][] loginData() {
return new Object[][] {
{“user1″,”pass1”},
{“user2″,”pass2”}
};
}
Q34. How do you retry failed tests?
Using TestNG RetryAnalyzer.
Selenium + Java + API Practical Example
Response response = RestAssured.get(“/users”);
System.out.println(response.getStatusCode());
Output
200
Framework Design Questions (3 Years Experience – Important)
Q35. What is Hybrid Framework?
Combination of POM + Data-Driven + Keyword-Driven frameworks.
Q36. How do you structure an automation framework?
- Base class
- Page classes
- Test classes
- Utilities
- Reports
Q37. Build tools you have used?
Maven or Gradle.
Q38. CI/CD tools experience?
Jenkins, GitHub Actions, Azure DevOps.
Common Mistakes in Java Interviews (3 Years Experience)
- Weak Core Java fundamentals
- Overusing Thread.sleep()
- Hard-coded test data
- Poor exception handling
- Not understanding framework design
1-Page Revision Table / Notes
| Area | Focus |
| Core Java | OOP, Collections, Streams |
| Selenium | Waits, Dynamic elements |
| TestNG | Parallel execution |
| Framework | POM, Hybrid |
| API | Rest Assured basics |
| CI/CD | Jenkins pipelines |
FAQs – Java Interview Questions for 3 Years Experience in Testing
Q1. What Java level is expected for 3 years experience?
Strong Core Java with real automation usage.
Q2. Are coding questions mandatory?
Yes, Java and Selenium coding is expected.
Q3. Is framework design asked?
Yes, POM and Hybrid frameworks are commonly discussed.
Q4. Is API testing required at this level?
Basic API automation knowledge is expected.